Issue #54 of Weekly Shonen Jump magazine has dropped some new information regarding the upcoming 4th season of Haikyuu!!. In particular, they revealed the series’ new theme song artistes!
According to the magazine, Burnout Syndromes will perform the OP song “PHOENIX”. Meanwhile, CHICO with Honeyworks will be the ones performing the new ED song titled “Kessen Spirit.” Burnout Syndrome previously performed the OP songs for both 2nd and 3rd seasons of the TV anime.
The anime will premiere in January 2020 as part of MBS’s Super Animeism timeslot. Production I.G. will once again be producing the series, and they have already confirmed some new cast additions. These include Kazuyuki Okitsu as Suguru Daishou, Natsuki Hanae as Kourai Hoshiumi, and Mamoru Miyano as Atsumu Miya.
Source: Weekly Shonen Jump issue #51